When I said 20%, I meant 20% at best during a normal 4 or 5 gallon cycle of oil. I am a BIG believer in changing oil often and would go with synthetic but the clearances on these old flatheads are bigger than newer cars with tighter clearances. That along with sythetic likes to find it"s way between gaskets and outside the engine doesn"t appeal to me.

There is an .040 hole at the inlet of the filter can.Oil pressure would be low without it.But it seems the oil flow at 40lb pressure could be calculated and the answer found.No mention of full flow filters leaking down and no oil to the bearings until the can is full.The poor quality of some filters comes to mind.

36 coupe said: (quoted from post at 05:40:07 05/09/13) There is an .040 hole at the inlet of the filter can.Oil pressure would be low without it.But it seems the oil flow at 40lb pressure could be calculated and the answer found.No mention of full flow filters leaking down and no oil to the bearings until the can is full.The poor quality of some filters comes to mind.

A few months ago I did a little spreadsheet calculation on oil flow inside the flathead so I just happen to have some numbers already on hand for you to chew on. I'll be happy to provide you with a copy of the spreadsheet if you would like to verify the algorithm or play with the clearance numbers to see what happens in a worn engine:

The cross sectional area of the .040 orifice in the filter housing is .0013 square inches.

Assuming "like new" journal oil clearances of .001 the sum total cross sectional area of the oil clearances in all of the journal bearings is .129 square inchs. That is just the flow area around the camshaft, main and rod journals and does not include oil squirt holes, wrist pins, etc.

Based on those basic numbers care to hazard a guess on what percentage of the oil pumped out of the sump goes through the filter? The oil filtering system on the N-series flathead is a joke.

I think that might be high - maybe someone that's really bored (hint) can pull the governor line off and measure the outflow. Then we wouldn't have to guess. :idea: Or does that bypass the bypass? TOH This post was edited by TheOldHokie at 07:50:50 05/09/13.

Quoting Removed, click Modern View to seeDon't you remember?!!?? I'm disappointed! I already did that back in Nov, 2009. One pint in 25 seconds at 25PSI on gauge. But then there is always those one or two drops that may not pass that way for weeks! :wink:

Now we have to find which drops didnt get through the filter.Quart a minute aint bad.Same system was used on Ford cars and trucks 1940 to 1953,must have worked.Now where are the 20% turkeys hiding?I have had a JD H running for a long time with the gas line disconnected.Not just on the gas in the bowl.Had to pull the ignition wires to stop it.

It "works" just not very well. The N-series oil pump produces several GALLONS per minute so we are back to that 20% or less number. Typical flow rate on a full flow filter is 10 gallons per minute. TOH

You dont have to filter oil that fast.Ford cars and trucks didnt get oil filters until 1940.They were an option.The Model A ran with no pressure on the rods, just had dippers that scooped oil from a tray in the oil pan.Primitive but it worked.My 6 volt tractor starts fine, why should I spend money on 12 volt conversion?

There are times when you can get too much information on a subject.In electronics practical demonstration was better than theory.I have never seen an electron but sure have felt them.Has anyone run a flow test on the Franz toilet paper filter?

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